1. Field of the Invention
The present invention relates to the field of content protection. More specifically, the present invention addresses the generation of pseudo random numbers for use in a symmetric ciphering/deciphering process based authentication process for authenticating video receiving devices.
2. Background Information
In general, entertainment, education, art, and so forth (hereinafter collectively referred to as “content”) packaged in digital form offer higher audio and video quality than their analog counterparts. However, content producers, especially those in the entertainment industry, are still reluctant in totally embracing the digital form. The primary reason being digital contents are particularly vulnerable to pirating. As unlike the analog form, where some amount of quality degradation generally occurs with each copying, a pirated copy of digital content is virtually as good as the “gold master”. As a result, much effort have been spent by the industry in developing and adopting techniques to provide protection to the distribution and rendering of digital content.
Historically, the communication interface between a video source device (such as a personal computer) and a video sink device (such as a monitor) is an analog interface. Thus, very little focus has been given to providing protection for the transmission between the source and sink devices. With advances in integrated circuit and other related technologies, a new type of digital interface between video source and sink devices is emerging. The availability of this type of new digital interface presents yet another new challenge to protecting digital video content. While in general, there is a large body of cipher technology known, the operating characteristics such as the volume of the data, its streaming nature, the bit rate and so forth, as well as the location of intelligence, typically in the source device and not the sink device, present a unique set of challenges, requiring a new and novel solution. Parent application Ser. Nos. 09/385,590 and 09/385,592 disclosed various protocol and cipher/deciphering techniques to authenticate a video sink device and protect transmission to the video sink device. Pseudo random numbers are employed as seed or basis numbers for the ciphering/deciphering process. Further, the video devices include embedded cipher units for performing the necessary ciphering and deciphering. The present invention addresses a novel approach to generate the required pseudo random numbers using the embedded cipher units, thereby eliminating the need to provide separate circuitry to generate the required pseudo random numbers.